1. Field of the Invention
The present invention relates to an image capturing lens system, and more particularly, to a compact image capturing system used in a portable electronic product.
2. Description of the Prior Art
In recent years, with the popularity of mobile phone cameras, the demand for compact imaging lenses is increasing, and the sensor of a general photographing camera is none other than CCD (charge coupled device) or CMOS device (Complementary Metal Oxide Semiconductor device). Furthermore, as advances in semiconductor manufacturing technology have allowed the pixel size of sensors to be reduced, and the resolution of compact imaging lenses has gradually increased, there is an increasing demand for compact imaging lenses featuring better image quality.
In a conventional PC camera or a camera lens with a wide field of view, the lens assembly is usually arranged in a manner that the front lens group has negative refractive power, and the rear lens group has positive refractive power. Such an arrangement for the purpose of obtaining a wide field of view forms the so-called inverse telephoto structure. U.S. Pat. No. 7,515,351 shows an example of said arrangement, disclosing a lens assembly comprising five lens elements with a negative front lens group and a positive rear lens group, wherein the third and fourth lens elements are adhered by means of two glass spherical surface lenses to form a doublet so as to correct the chromatic aberration. Such an arrangement of optical elements, however, has the following disadvantages: (1) the degree of freedom in arranging the lens system is curtailed due to the employment of excess number of glass spherical surface lenses; thus, the total track length of the system cannot be reduced easily; (2) the process of adhering the glass lenses together is complicated, posing difficulties in manufacture.
Therefore, a need exists in the art for an image capturing lens system that is applicable to electronic products, employs simple manufacturing process and maintains a moderate total track length.